This invention relates generally to methods for controllably coating the surfaces of particles with smaller sized colloidal particles. More specifically the present invention relates to processes for forming colloidal particles of useful surface additives, such as an organocarboxylate metal salt and other lubricant or release agent additives, on the surface of suspended resin particles, such as toner particles.
The present invention in turn provides improved toner compositions and imaging processes thereof. The imaging processes of the present invention provide toners and methods of preventing or eliminating background deposits and spotted images and which spots are believed to arise from fugitive aforementioned lubricant or release agent additives that have escaped from the surface of the toner resin particles and result in objectionable deposits in the developer housing, on the imaging member, and on the image itself.
The toner compositions of the present invention in embodiments thereof possess excellent admix characteristics, maintain their triboelectric charging characteristics for an extended number of imaging cycles, and enable the elimination or minimization of undesirable background deposits or spots on the imaging member or photoconductor, and the image receiver sheet or copy paper. Furthermore, the toner compositions of the present invention are substantially insensitive to relative humidity in a machine environment and permit developed images with excellent optical densities and low background. Developers of the present invention are comprised of the aforementioned toners and carrier particles, especially carrier particles comprised of a core with a mixture of polymers thereover. The toner and developer compositions of the present invention can be selected for electrophotographic, especially xerographic and ionographic, imaging and printing processes and preferably ionographic version of magnetic image character recognition processes (MICR) such as processes similar to those selected for the Xerox Corporation 8790/9790 MICR machines, and preferably the Xerox Corporation 4135.RTM. MICR test fixture or machine, and wherein for example, personal checks with no, or minimal background deposits can be generated.